Filamentous fungi

The majority of fungi form filamentous structure known as hyphae. These are multicellular structures with branching. Most of these hyphae extend in 3 dimensions through whatever they are growing in. Specialised hyphae are produced to allow vegetative (non-sexual) reproduction with spores or conidia. Some highly specialised reproductive or protective structures are also formed by some species, such as ascospores. There are probably millions of species in total. Filamentous fungi (also known as moulds) are found in most phylogenetic groups, but the vast majority of human pathogens are Ascomycetes.

Factsheets

Alternaria

NAMES
Alternaria alternata
NATURAL HABITAT
Found in soil, air and it has also been described on normal human and animal skin and conjunctiva.
GEOGRAPHY
Worldwide
FREQUENCY
It is frequently associated with allergic respiratory disease. It is an infrequent case of localised and disseminated infections.
DISEASES
– Allergic respiratory disease, including thunderstorm asthma and SAFS (watch an interview with a patient with allergic bronchopulmonary mycosis)
– Allergic fungal rhinosinusitis
– Opportunistic infections in immunocompromised hosts, including in skin, paranasal sinuses and lungs.
– Keratitis, peritonitis, osteomyelitis, sinusitis, endophthalmitis, and cutaneous and subcutaneous infections associated with a previous trauma.
CULTURE
Fast-growing colonies, grey to black and powdery to floccose. Microscopically, conidiophores arise from septate hyphae. Multicellular conidia are produced sympodially in chains (usually composed of more than 5 conidia). Conidia are obclavate, pyriform to ovoid or ellipsoidal up to 50 mm long and 3-12 mm wide. Brown pigmented with smooth to verrucose surface.
Biosafety level 2
ANTIFUNGAL RESISTANCE
This species is resistant to fluconazole. Resistance to itraconazole and voriconazole have been described and some strains have shown in vitro resistance to amphotericin B.
INDUSTRIAL USES
Biocontrol of some weed plants.

Apophysomyces

NAMES
Apophysomyces species (A. elegans, A. ossiformis, A. trapeziformis, A. variabilis) are clinically identical and difficult to distinguish by traditional diagnostics, so they are included together here.
NATURAL HABITAT
Isolated in soil and decaying plant debris.
GEOGRAPHY
Worldwide, but more frequent in tropical and subtropical areas
FREQUENCY
Unlike other Zygomycetes, frequency of infection is more common with immunocompetent hosts. The real frequency is unknown but it is far more common in tropical and subtropical areas. A. trapeziformis has recently been identified as the cause of mucormycosis in 13 survivors of the Joplin tornado in Missouri, USA (read the story at Medscape). 
DISEASES
Most commonly cutaneous and subcutaneous infections following the traumatic implantation of the spores.
Sinus infections have also been described. 
CULTURE
Great expertise is required to differentiate the three species of the complexExperts can distinguish them by the morphology of their sporangiophores and sporangiospores. It is advisable to confirm identify by means of DNA sequencing the ITS fragment.
Fast growing; pale white turning brownish-grey with age. Microscopically, pyriform sporangia, apophyses funnel or bell-shaped. Sporangiospores are different depending on the species being bone-shaped, trapezoid-shaped or variable-shaped.
Biosafety level 2
ANTIFUNGAL RESISTANCE All isolates are intrinsically resistant to fluconazole, ketoconazole, voriconazole and the echinocandins. Usually susceptible to amphotericin B and posaconazole. Variably susceptible to itraconazole.
INDUSTRIAL USES
None
Apophysomyces variabilis

Cladosphialophora

NAMES
Cladosphialophora spp. Includes C. carrionii, Cladosphialophora bantiana, and others.
NATURAL HABITAT
Soil and rotten plant material
GEOGRAPHY
Worldwide distribution, especially semi-arid regions
FREQUENCY
Unknown
DISEASES
Cladosphialophora spp. are causative agents of phaeohyphomycosis, chromoblastomycosis, and mycetoma. Species of this genera have been isolated from cutaneous, subcutaneous and disseminated infections. C. bantiana causes cerebral phaeohyphomycosis in immunocompetent patients.
CULTURE
Colonies restricted powdery to woolly, olivaceous green to black. Conidiophores are mostly absent or not well developed; unicellular conidia in chains without pigmented scares.
Biosafety level 2: C. carrionii
Biosafety level 3: C. bantiana
ANTIFUNGAL RESISTANCE
Intrinsically resistant to fluconazole. High MICs to echinocandins and some strains show high MICs to amphotericin B.
INDUSTRIAL USES
None
Spore chains of Cladophialophora spp.

Fonsecaea

NAMES
Fonsecaea pedrosoi complex which includes F. monophora and the previously named species F. compacta, now incorporated in F. pedrosoi complex.
[ Teleomorph = Hormodendrum pedrosoi ]
NATURAL HABITAT
Rotten wood and soil
GEOGRAPHY
Worldwide distribution, especially in humid areas.
FREQUENCY
Unknown
DISEASES
It is the main agent of human chromoblastomycosis. It has also been isolated from cases of keratitis, paranasal sinusitis and brain abscess.
CULTURE
Colonies are slow growing, lanose to velvety, olivaceous to black. Microscopically it is characterized by dark brown hyphae and suberect conidiophores loosely branched. Phialides with funnel-shaped collarettes and/or simpodial growth might be present. All strains grow at 37C but not at 40C.
Biosafety level 2
ANTIFUNGAL RESISTANCE
Some strains show elevated MICs to AMB. Echinocandins have none or low activity against this species.
INDUSTRIAL USES
None
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